It is known to seal the piston rod of crosshead piston compressors movably supported in an oscillating manner with the aid of dry-running or lubricated friction sealing elements. The seal along the piston rod takes place via so-called packings which are usually structured in the form of a serial connection of single-part or multipart sealing elements.
The different variants of packings with seal arrangements can roughly be divided into seal arrangements with single-part sealing rings and with multipart sealing rings.
Document WO 97/00397 discloses a multipart sealing ring which comprises three segments. These segments are subject to wear during operation, with the segmentation of the sealing ring having the consequence that the contact pressure of the segments on the piston rod, and thus the sealing effect, is maintained up to a predefined wear limit despite the wear thanks to a self-adjustment of the segments. Such a multipart sealing ring thus has a wear compensation in that the segments are automatically displaced in dependence on the wear.
Document WO 97/00396 discloses a single-part sealing ring which is suitable as a piston rod seal arrangement. This sealing ring includes an individual single-part ring having a ring gap. With this sealing ring, the wear compensation takes place by an elastic and/or plastic deformation of the sealing ring.
The sealing rings of a piston rod packing are pressed toward the piston rod by a coil spring, for example, in the unloaded state. An additional pressing of the sealing ring toward the piston rod takes place by the differential pressure applied to the sealing ring during the operation of the compressor. In particular with segmented sealing rings, but also with single-part sealing rings with a ring gap, the changing pressure engaging at the sealing ring effects an elastic and/or plastic deformation of the sealing ring or of the individual segments, which has the consequence, among other things, of an unequal material removal along the periphery of the sealing ring. These effects in particular occur with seal arrangements arranged directly toward the sealing space since these seal arrangements are usually loaded with a pressure difference fluctuating over time. The load has the consequence that this seal arrangement has a rapidly decreasing sealing effect and that a flow or a break failure of the seal arrangement respectively occurs in dependence on the material used for the sealing rings.
Known seal arrangements thus have the disadvantage that they may have a rapidly decreasing sealing effect or a relatively high wear under certain circumstances.